docs: def verify_checksum(*lines):
      """Verify the checksum of one or more TLE lines.
  
      Raises `ValueError` if any of the lines fails its checksum, and
      includes the failing line in the error message.
  
      """
      for line in lines:
          checksum = line[68:69]
          if not checksum.isdigit():
              continue
          checksum = int(checksum)
          computed = compute_checksum(line)
          if checksum != computed:
              complaint = ('TLE line gives its checksum as {}'
                           ' but in fact tallies to {}:\n{}')
              raise ValueError(complaint.format(checksum, computed, line))